Print Even and Odd Numbers Using (Two Threads) Completable Future and Executor Service
A code snippet to print Even and Odd numbers using multi-threading.
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Join For FreeYou might have seen this question being asked in so many interviews.
We are going to achieve this using Java 8 completable future and executor service.
- We have created two single-thread executors and assigned a name to them.
- Using IntStream we are iterating from 1 to 101.
- Using two completable futures to check odd or even and calling join after the call so that the completable future will finish its execution.
- Shutting down the executor services in the end.
Java
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.stream.IntStream;
public class Solution{
public static void main(String[] args) {
ExecutorService firstExecutorService = Executors.newSingleThreadExecutor(r -> {
Thread t = new Thread(r);
t.setName("first");
return t;
});
ExecutorService secondExecutorService = Executors.newSingleThreadExecutor(r -> {
Thread t = new Thread(r);
t.setName("second");
return t;
});
IntStream.range(1, 101).forEach(num -> {
CompletableFuture<Integer> thenApplyAsync = CompletableFuture.completedFuture(num).thenApplyAsync(x -> {
if (x % 2 == 1) {
System.out.println(x + " " + Thread.currentThread().getName());
}
return num;
}, firstExecutorService);
thenApplyAsync.join();
CompletableFuture<Integer> thenApplyAsync2 = CompletableFuture.completedFuture(num).thenApplyAsync(x -> {
if (x % 2 == 0) {
System.out.println(x + " " + Thread.currentThread().getName());
}
return num;
}, secondExecutorService);
thenApplyAsync2.join();
});
firstExecutorService.shutdown();
secondExecutorService.shutdown();
}
}If you run the above code you will see the following logs in the console.
Executor (software)
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